This invention relates to a cylinder head construction for a direct-injected internal combustion engine and more particularly to an improved configuration for the nozzle-receiving opening that receives the fuel injector in the cylinder head.
Because of the potential advantages of better fuel economy and exhaust emission control as well as improved output, direct cylinder fuel injection is being considered for many engine applications. However, when the engine is of the high performance type, the placement of the fuel injector in the cylinder head gives rise to a number of problems, not the least of which is the placement of the fuel injector.
The relationship between the fuel injector and its spray pattern and the spark plug and their relative locations in the cylinder head and combustion chamber are quite important. In a preferred arrangement, the spark plug is generally centrally positioned in the cylinder head and the fuel injector is mounted at a peripheral edge of the combustion chamber recess and injects generally downwardly toward the cylinder bore axis.
This location for the injector means that it should be positioned in such a manner that it does not interfere with the flow passages into the cylinder and out of the cylinder. This is particularly difficult when multi-valve engines are employed, as is typically with the type high performance engine that also would use direct cylinder fuel injection.
With four valve per cylinder engines, it has been proposed to position the fuel injector between and below a pair of like passages that serve the combustion chamber. This generally results in the injector being disposed at a relatively small acute angle to the sealing surface of the cylinder head that engages and seals the cylinder block around the cylinder bore.
Conventionally, the fuel injector is mounted in an injector well formed in the cylinder head which generally is a counter-bored passageway having its smaller diameter portion extending through the combustion chamber surface of the cylinder head.
As a result of this configuration, the opening of this fuel injector well through the cylinder head surface defines a sharp edge, particularly along the radially outermost portion of the combustion chamber surface. This sharp edge is subjected to contractions and expansions when the engine is stopped and started due to the change in temperature and the fact that the cylinder head fasteners are disposed outwardly from this opening. As a result, cracking or erosion is likely to occur at this sharp edge that can give rise to stress effects that are a source of potential damage to the cylinder head.
It is, therefore, a principal object of this invention to provide an improved cylinder head construction for a direct injected internal combustion engine.
It is a further object of this invention to provide an improved fuel injector well arrangement for a cylinder head that permits the desired placement of the fuel injector but eliminates stress risers that can cause potential damage.
It is a further object of this invention to provide an improved spark plug well configuration for a direct injected cylinder head.